1. Field of the Invention
The present invention relates to an electric three-way valve which circulates refrigerant of an air-conditioner and a refrigerator and switches a passageway.
2. Description of the Related Art
In general, there is known a valve which uses a motor, for example, a step motor, installs a gear in a shaft end portion of a rotor of the motor, and blocks one passageway opened to a valve seat by rotating a valve core in the valve seat in a sliding manner using a driving force generated by the meshing between the gear and a gear driving the valve core (see Japanese Patent Literature 1, that is, JP 03-28583 A). Furthermore, there is known a valve which controls an opening degree of an opening by a valve core driven so as to slide on a valve seat by a driving force generated by a gear as described above (see Japanese Patent Literature 2, that is, JP 2000-346227 A).
In the typical valve which uses the valve core rotating so as to slide on the valve seat, a casing which accommodates the valve core and the gear is integrated with a housing which includes the rotor of the motor therein. For this reason, there is a case in which a wall which constitutes the housing and is formed of a non-magnetic material, for example, stainless steel is relatively thickened. When the housing is thickened, the magnetic characteristics of the step motor are degraded and the torque of the motor decreases. Accordingly, in order to obtain a predetermined torque of the motor, there is a need to increase the output of the step motor. As a result, an electric three-way valve (or an electric switching valve) increases in size and a space occupied by the electric three-way valve when configuring a refrigerant circulation system increases in volume.
Furthermore, in the typical valve core which rotates in a sliding manner, the shape of the valve core which may easily and smoothly slide on the valve seat is not taken into consideration.